A hat including a crown with a base. An outer headband layer is affixed to the crown at the base by a base seam that extends around a circumference of the crown. an inner headband layer is affixed to the outer headband layer at a position opposite the base to define a circumferential pocket between the outer headband layer and the inner headband layer. A rail has a T-shaped cross section disposed in the pocket. The T-shaped cross section is defined by a stem and an arm. The rail is affixed to the outer headband layer and the inner headband layer by a first rail seam through the stem, the outer headband layer, and the inner headband layer. The rail is further affixed to the outer headband layer by a second rail seam only through the outer headband layer and the stem. A bill has a track with a figure four shaped cross section affixed thereon. The track has a channel that receives and retains the rail therein to guide the bill around the crown.